The present invention particularly relates to a machine used in the opthalmic profession for the fitting and/or glazing of lenses in eyeglass frames. These frames made of thermoplastic materials must be properly warmed to soften them to allow insertion of the lenses or to bend and form them to fit the face and head of the user. The warming of frames has been accomplished in many ways such as by hot plates, hot air blowers, and infra-red lamps, but none of these were satisfactory since the operator in all cases would never know when the plastic material was warm enough to bend without cracking and when too hot it would blow or sponge and then scorch.
My "Air Tempering Device" U.S. Pat. No. 2,789,200 issued Apr. 16, 1957 was created to eliminate these difficulties and faults. In this patent air is tempered or warmed to a precise temperature for use in warming the thermoplastic, thus warming it in a short period of time and yet never allowing overheating of the air stream to cause scorching.
In all previous warmers that used infrared rays for heating, the warming and scorching problems were aggravated since the color of the thermoplastic or its transparency to the rays affected its response to heat absorption, and by the necessity for critical distance gaging, due to the fact that the temperature varied by the square of the distance from the source.
In all of these examples the infrared ray radiation sources were of very high temperature and of concentrated origin or from a very small high temperature radiator.
The term radiation refers to the continual emission of energy from the surface of all bodies. This energy is called radiant energy and is in the form of electromagnetic waves. These waves travel with the velocity of light. When they fall on a body which is not transparent to them they are absorbed and their energy converted to heat.
The radiant energy emitted by a surface, per unit of time and per unit area, depends upon the nature of the surface and on its temperature. At low temperatures the rate of radiation is small and the radiant energy is chiefly of relatively long wavelength. As the temperature is increased, the rate of radiation increases very rapidly, in proportion to the 4th power of the absolute temperature, also the wavelength shifts toward shorter wavelengths. At each temperature a radiator might be radiating at, its radiant energy emitted is a mixture of waves of different wavelengths.
One general object of this invention, therefore, is to provide a new and improved infrared radiation type of machine for warming eyeglass frames or the like of thermoplastic material. More specifically, it is an object of this invention to provide a machine of the character indicated which will emit temperature controlled heat rays to warm eyeglass frames to a temperature not exceeding the scorch temperature of the particular plastic being heated.
Another object of the invention is to provide radiation of heat rays to more than one side of the object to be heated.
Another object of this invention is to provide lenticulated surface radiatiors for focusing heat rays from locations on the radiators where not needed, to where more heating is needed on the article.
A further object of the invention is to provide thermostatically controlled radiators having integral heating elements.
A still further object of the invention is to provide an infrared radiator having the temperature of its radiation controlled by an increase or decrease in the frequency or wavelength source.
Another object of this invention is to provide for quick disassembly of the case from the parts that might require service by having these parts all on one base, thus making servicing as simple as possible and providing a single location for electrical connections to the power cord.
A further object is to eliminate the need of acquiring the skill to know how far away the unit to be heated must by held from the heat source to prevent burning.
Another object is to prevent the danger of exposing the operator's eyes to high intensity infrared rays.